1. Field of the Invention
The invention relates generally to an ink storage unit and, more particularly, to an ink storage unit that can prevent reverse ink flowing causing ink leakage.
2. Description of the Related Art
Due to its advanced development, inkjet printing technology is broadly implemented in many types of printing apparatuses such as printers or facsimile machines. Inkjet printing technology principally consists of an inkjet print head that produces a high pressure to eject ink droplets out of the print head on the printed document, thereby forming an ink point thereon. By an adequate disposition of the numerous ink points on the printed documents, characters or graphics hence are formed. To continuously supply the inkjet print head with ink, an ink storage unit is traditionally used to store ink.
To prevent ink leakage out of the ink storage unit, a method of the prior art uses a pressure regulator that is disposed within an ink tank of the ink storage unit. The pressure regulator adequately regulates a pressure differential between the interior and the exterior of the ink tank by creating a negative pressure that keeps the ink from leaking out. Another method known in the prior art is to arrange an ink storage body made of porous material such as sponge or fabric within the ink tank. Via capillary action of the porous ink storage body, the ink can be stored and retained within the ink tank.
FIG. 1 is a sectional view that schematically illustrates the construction of an ink storage unit known in the prior art. As illustrated, a traditional ink storage unit 100 principally comprises an ink tank 110 that defines a confinement space 112 in which an ink storage body 120 is placed. The ink storage body 120 is made of a porous material such as sponge that enables to store and retain ink within the ink tank 110 by capillary action. The ink tank 110 further includes an ink outlet 114 at a lower side to output ink to an ink-ejecting member 300. An upper side of the ink tank 110 is further provided with an air inlet 116 through which air is enabled to penetrate the confinement space 112 of the ink tank 110. While the ink is outputted through the ink outlet 114, the external air simultaneously penetrates into the ink tank 110 through the air inlet 116 so as to achieve an adequate pressure balance of the confinement space 112 with respect to the external pressure. Ink output through the ink outlet 114 can be thereby sustained to supply the ink-ejecting member 300.
The introduction of ink within the ink tank 110 is usually achieved via ink injection by means of a syringe inserted through the air inlet 116 to the lower half of the ink storage body 120. However, ink stored in the ink storage body 120 may flow along the interface 130 between the outer surface of the ink storage body 120 and the inner sidewall of the ink tank and leak out through the air inlet 116. Therefore, the prior art further disposes a notch 121 on the outer surface of the ink storage body 120 facing the air inlet 116. The outer surface of the ink storage body 120 at that location is thereby separated a higher distance from the air inlet 116. Ink flowing through the interface 130 thus cannot contact with the air inlet 116 at the location of the notch 121 and, consequently, ink leakage is prevented.
However, the above disposition becomes deficient when the ink storage unit 100 is subject to significant external shaking, and ink leakage through the air inlet 116 hence still occurs.